I've grafted a cummins intake heater grid onto my toyota 2L engine to assist with wintertime starting. It works great and I was able to start the engine at 17 F tonight with just the grid heater, no glow plugs. I use a momentary switch to energize the grid.

Does anybody know how these heaters are operated in the cummins engine i.e. How long do they typically warm up before giving you the go ahead to start the engine and how long can they be energized before you run the risk of burning them out?

They typically remain energized for a few seconds and then turn off for a few seconds. This causes lots of posts on Cummins' forums when cold weather comes around. Folks think something is wrong with their truck. The ones that surprise me are the guys with a decent post count and have all these other mods on their truck then have no clue why they get dimming!

Anyway..I'm not certain but I believe they cycle on and off to keep from burdening the vehicles system for very long.

I saw a Cummins bulletin stating that each grid heater drew 110 amps @ 12V. So two of them will draw 220A @ 12V. BUT this is a dynamic system, with that much current the system can not stay at 12V. Mine will usually drop down to about 8V.

So with both at a full 12V you're getting 2640 watts, but at 8V this drops to around 1173W (using ideal conductors, the resistance won't actually be constant). This may actually be the reason the heaters cycle. To give the heaters more 12V time so they can heat more efficiently. Trying to continue to power them at 8V or lower isn't getting the most bang for your buck... who knows!

Anyway, offhand the wait to start light stays on for about 10 or 15 seconds before going off. Then will cycle for about 3~5 seconds while idling.

As long as you have airflow through them and are cooling them I don't think you'll burn them out. Also as long as you have adequate size wire feeding the heaters you are fine there too.

I would do like Dodge and cycle them until the voltage drops to about 8V then let it recover.

I know that was kinda vague and rambling but I can't find any hard info on the times and am just going on the times I remember off the top of my head from the last time I started mine a couple days ago!

The 89-early 91 DODGES used a seperate module just for the grid heaters. The 90+ came on at 59 and the early ones wouldn't turn the heaters on until 12 degress. This what I read over on DTR. You could probably go to CUMMINS and get a controller for one though. Almost all of the CUMMINS 3.9's, 5.9's and 8.3's used a grid heater for starting and had a controller for them. If you want to go the manual route, I wouldn't hold them on for more than 10 seconds at 30 degrees. IIRC they were only actuated for roughly 8 seconds at freezing temps, but would come on right after start-up to keep the white smoke down. You also have to remember not to draw your voltage down to much as this could kill your alternator. The DODGE system is said to drop the alternator off line when cycling the heaters to prevent damaging the alternator.

Yes, the Dodge system does drop the alternator offline during grid heater operation.

Folks who have grid delete spacers report that the truck goes through the motions of pulsing the heaters. The voltmeter will drop when the heaters were supposed to be on because the alternator is offline.

On then 5.9 Cummins they're located at the base of the air horn on the right side of the engine if you standing in front of the truck facing the cab. I know they're in the same location on the B3.3, B3.9 and C8.3 engines as well.

They heat enough air to start because they are huge for a 12V system. When energized they draw 220A @ 12V and the voltage drops big time from there.

Here is the replacement air horn from Glacier. Click on the picture with the blue horn and you can see the location. The grid heaters in this picture have been replaced with the replacement block above. But you can see where they're supposed to be, between the base of the horn and the intake.http://www.glacierdieselpower.com/pr...pf_id=0307-PFI

220 Amps? That would explain why my 8 gauge wire is getting a little warm feeding both grids at the same time. I'm also using a relay off of a Volvo diesel rated for 80 amps so I need to upgrade solenoids as well.

I've left the grids energized for up to 20 seconds, but based on the current draw, I'm not getting enough juice to them to burn them out at 20 seconds. The grid came with I believe some 6 gauge or heavier ground wire (only 4 inches of it), so I visited at least a dozen auto stores, battery stores and the like trying to find some heavy gauge wire to feed the grids. My next bet will be to go to a welding store and see if they have some 6 gauge wire I could use.

I started the truck this morning at 10 F with no drama. Both my grids and the glow plugs are on manual switch controllers and I turn them off before cranking over the truck to maximize starter speeds.

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